A metal coping is used in dentistry in the construction of a dental crown and bridge. The metal coping functions as the understructure of the crown and is usually covered with a fired on coating of a ceramic or acrylic composition for purposes of aesthetics. The metal coping supports the coating and provides the structural strength and rigidity for the restored tooth to resist the force of mastication.
A metal coping has recently been developed for constructing a porcelain to metal crown which can be formed without waxing, investing or casting. The coping is described in U.S. Pat. Nos. 4,459,112 and 4,492,579 and consists of a thin metal foil of two or more layers of metal having a prefabricated geometry with a plurality of foldable sections. The foldable sections are folded over when the foil is adapted to the die so that they overlap. The unfolded metal foil is very thin, generally between about only 15 to 100 microns in thickness which permits the foil to the readily adapted to the die. However, once the foldable sections are folded over, the foil thickness is increased by the number of folded over layers of metal.
After the coping is adapted to the die, it is heat treated which sinters the overlapping folds one another forming a unitary mass. The coping, in its final form, possesses substantially increased strength and rigidity relative to the unfolded metal foil.
The amount of force which the coping must endure to maintain the integrity of the restoration depends upon the tooth to be restored which in turn depends upon the location of the tooth in the mouth. Posterior teeth, particularly molars, need to be much stronger than anterior teeth and accordingly require a stronger coping. The metal foil of the present invention will form a coping of substantial strength and resistance to fracture.